Project Summary/Abstract Optimism ? a cognitive bias to overestimate positive future outcomes ? likely plays a critical function in early childhood, serving as a catalyst for how children learn, confront challenges, and navigate social relationships. Roughly 80% of adults make optimistically biased predictions, and although optimism is adaptive and provides motivational, social, and health benefits, virtually no empirical research has tested how and when optimism develops. Further, lack of optimism, either presented as realism or pessimism, is associated with depression in adults, and may be driven by early adversity. Our broad predictions are that optimism is present early in broad capacity and influences how children learn from and about the world. As they experience event outcomes, and probabilistic reasoning improves, the magnitude of their optimistic predictions diminishes. Further, divergent developmental trajectories may emerge such that optimism declines more steeply in children who experience more adversity, compounding the disadvantages they face. Lack of early optimism may also be a key symptom of preschool depression and/or perpetuate symptoms over development. The proposed study comprises a unique research team with expertise in cognitive development, early childhood emotion/depression, and developmental neuroscience, to address key questions about how early adversity impacts the development of optimism, and characterize underlying neural processes that reflect optimistic predictions. This multi-method interdisciplinary approach will provide behavioral data on how key elements of optimism are expressed and maintained in high- and low- risk 3- to 8-year old children over time, and neural activation data using event related potentials (ERP) to assess children's neural response to reward feedback. We recently developed and tested two experimental tasks to assess optimism in a racially and socioeconomically diverse sample of 180 3- to 6-year-old children, many of whom are growing up in poverty. The proposed project will re-test our captured high- and low-risk sample 1 and 2 years after their initial completion of the optimism tasks, and enroll a new cohort of children to be tested at 2 timepoints. At each timepoint we will collect parent- reports that assess children's life experiences (positive and negative), depressive symptoms, motivational style, and family dynamics. Further, recent research implicates neural reward circuitry in the maintenance of optimism in adults, raising the possibility that reward processing facilitates or maintains optimism in early childhood; in contrast, blunted neural response to reward has been found in children with depression and adolescents who faced early adversity. Thus, an established ERP reward processing task will be administered to all children during their second session to test whether more optimistic children show stronger reward circuitry activation to positive outcomes than less optimistic children. This ERP measure will also provide foundational information about the development of reward processing in a high-risk sample of young children, many of whom face adversity and thus are more likely to demonstrate blunted neural response to reward in adolescence relative to their low-risk peers. Our findings have the potential to indicate a shared mechanism of depression and non-optimism, and to elucidate protective factors indicative of resiliency, and risk factors that compound disadvantages of children facing adversity, that can be targeted for preventative interventions at the earliest possible point.